Sensing means for air-conditioning systems and the like

ABSTRACT

A thermistor for effecting control of a heat exchanger in an air-conditioning system is located in a closed ended tube inside an air duct and extending transversely thereof. The tube has a series of spaced openings in a first section thereof which faces upstream of the moving air in the duct and a second section of the tube has a single opening facing downstream. The thermistor is located in a closed wall section of the tube intermediate the first and second sections. The total area of the single opening facing downstream is greater than the total area of the openings facing upstream, and the area of the cross section of the tube interior is greater than the total area of the ports facing upstream. In one form of the invention the areas of the openings in the tube facing upstream progressively increase as the distance of the openings from the transistor increase.

Unite States Patent Continuation-impart 0! application Ser. No. 852,402,Aug. 22, 1969, now abandoned. This application Mar. 4, 1970, Ser. No.16,289

[54] SENSING MEANS FOR AIR-CONDITIONING SYSTEMS AND THE LIKE 13 Claims,5 Drawing Figs. [52] US. Cl 62/227, 73/359 [51] Int. Cl F25b 1/00 [50]Field of Primary ExaminerMeyer Perlin Attorney-Watts, Hoffmann, Fisher &Heinke ABSTRACT: A thennistor for effecting control of a heat exchangerin an air-conditioning system is located in a closed ended tube insidean air duct and extending transversely thereof. The tube has a series ofspaced openings in a first section thereof which faces upstream of themoving air in the duct and a second section of the tube has a singleopening facing downstream. The thermistor is located in a closed wallsection of the tube intermediate the first and second sections. Thetotal area of the single opening facing downstream is greater than thetotal area of the openings facing upstream, and the area of the crosssection of the tube interior is greater than the total area of the portsfacing upstream. In one form of the invention the areas of the openingsin the tube facing upstream progressively increase as the distance ofthe openings from the transistor increase.

PATENTEDJAN 41972 3631,68.

Eff

INVENTORS FIG.5 ROBERT E. BROOKS JOHN M. EWART JAMES E. RANDALLATTORNEYS SENSING MEANS FOR AIR-CONDITIONING SYSTEMS AND THE LIKERELATED APPLICATIONS The present application is a continuation-in-partof U.S. Ser. No. 852,402, filed Aug. 22, 1969, Group 345 and nowabandoned.

BACKGROUND OF THE INVENTION It is desirable to control the operation ofan air-tempering or conditioning system according to the sensedcondition of air passing through a distribution duct or the like andcertain control apparatus for this purpose comprise a sensor elementwhich is relatively minute, such as a thermistor. It has been found thatair forced through the usual air ducts is not uniform in the conditionto be controlled, such as temperature, throughout the cross section ofthe duct and therefore a small sensor merely located in the duct cannotbe relied upon to indicate the average condition of the air.

THE PRESENT INVENTION The principal object of the present invention isthe provision of a new and improved means for subjecting a relativelysmall sensing element to a flow of air which is representative of theaverage or mean condition of air flowing in an air duct of anair-conditioning or tempering system.

More specifically, it is an object of the present invention to provide atubular air conduit structure in an air duct of an airconditioningsystem and having sidewalls extending transversely of the air flowing inthe duct, a first section of the walls of the tubular structure having aseries of spaced openings therealong facing upstream so as to receive aplurality of relatively small air streams into the tube from a pluralityof locations transversely of the flow of air, and an opening in thewalls of a second section of the tube facing downstream, and a sensorelement in the tube between the first section of the tube and the outletfacing downstream so as to be subjected to the air in the tube flowingto the outlet. The total area of the openings facing upstream is lessthan the area of the opening facing downstream, and less than thecross-sectional area of the tube so that air will enter the tube throughthe upstream facing openings, mix in the tube and exit through theoutlet opening facing downstream and in so doing cause a mixture of airto flow over the sensor which is representative of the average aircondition in the duct. In some instances, particularly where the airduct is relatively wide or deep, the air flow may be characterized byvelocity patterns as well as wide temperature gradients. When these areapt to be present the openings in the tubular air conduit facingupstream are preferably graduated in size or area so that the openingswhich are locate increasingly distant from the sensor element areprogressively larger in area. The optimum areas of such openings can bedetermined by calculating the openings to provide the increase in volumeof air entering the duct required to compensate for the longer flow pathfrom a particular opening to the outlet opening.

Other objects and advantages of the invention will be apparent from thefollowing description of a preferred form thereof, reference being madeto the accompanying drawings wherein:

FIG. 1 is a more or less schematic view of a room air conditioner systemembodying the invention, certain elements of the conditioner systembeing shown broken away;

FIG. 2 is a fragmentary broken away view of an air temperature sensingtube and a sensor element therein;

FIG. 3 is a fragmentary top view of the tube shown in FIG.

FIG. 4 is a sectional view of the tube taken on line 4-4 of FIG. 3; and

FIG. 5 is a view similar to FIG. 2 but showing a different form of theinvention.

Referring to the drawings, a conventional air-conditioning system 10 isshown for cooling and dehumidifying the air of a room, not shown. Theair-conditioning system 10 include a compressor-condenser-evaporatortype refrigerating apparatus shown schematically at 11 which furnisheschilled air to an air duct 12 for distribution into a room, or the like,The duct 12 includes a blower, the motor of which is shown at 13, whichforces air from the refrigeration apparatus 11, through the duct 12 andinto a room through a grille 14, as is indicated by arrows 15.

The operation of the refrigerating apparatus 11 is controlled by a roomthermostat and also in accordance with the temperature of the airdischarged through the grille 15. This control is efiected by aconventional control apparatus, not shown in detail, which includes athermistor 16 having relatively small dimensions. It has been found thattempered air blown through a duct is not a uniform temperaturethroughout the cross section of the stream but has strata of differenttemperatures. It is therefore impractical to rely on controlling therefrigerating system 11 according to the temperature of a relativelynarrow strata of air in the duct to which the thermistor 16 wouldrespond if it were subject directly to the air stream in the duct.According to the present invention the thermistor 16 is subjected to anaveraging of the temperatures of the various strata of air in the airstream passing through the duct 12. This averaging is accomplished bylocating the thermistor within a sensor tube 17.

The tube 17 is cylindrical and of uniform diameter and extends across asubstantial portion of the duct 12 so that the walls thereof projecttransversely to the flow of air through the duct. In the form shown, thetube 17 is supported adjacent the top wall of the duct 12. The ends ofthe tube 17 are closed by end walls 20, 21. A series of openings 22 areformed along one section of the tube 17 towards the end wall 21. Theopenings 22 are preferably spaced equidistant apart and they are locatedin a section of the tube extending approximately half the width of theair duct. The openings 22 are arranged to face upstream with respect tothe air traveling through the duct 12. A relatively large opening 23 isformed in a section of the tube 17 adjacent the end wall 20 and facesdownstream with respect to the airflow through the duct 12.

The thermistor 16 is suitably supported on the axis of the tube 17intennediate the opening 22 most remote from the end wall 21, and theopening 23. Wires or leads 24, 25 extend from the thermistor l6 and passthrough a dielectric plug 26 in the wall of tube 17 to the controlapparatus for the refrigerating system 1 1.

It should be noted that the sum of the areas of the openings 22 is lessthan the area of the opening 23. Further, the cross sectional area ofthe tube 17 is greater than the sum of the areas of the openings 22.These relative areas promote a positive flow of air into the tube andaround the thermistor 16.

In operation, relatively small air streams across a substantial sectionof the air duct 12 enter the openings 22, mix within the tube 17, passover the thermistor 16 and exit through the opening 23. It has beenfound that the air entering the tube 17 and passing towards the opening23 is so intermixed that the temperature of the air actually contactingthe thermistor 16 will be an average of the temperature of the variousstrata of the air directed through the duct 12. Thus, the thermistor 16will accurately sense the mean temperature of the air discharged fromthe register 14. This will be true regardless of the variation in airvelocity in the duct. Furthennore, it will remain effective although thetube 17 may be rotated on its axis up to 60 on either side of the lineof direction of the air normal to the surface of the openings 22 whichis indicated at 30 in FIG. 4.

In some instances more satisfactory results are obtained if the openings22 of the tube 17 gradually increase in area towards the end of the tube21 which is remote from the sensor 16. This modification is particularlyappropriate where the air duct in which the tube is to be located isrelatively wide and the tube 17 therefore relatively lengthy.

This form of tube is shown at 17' in FIG. 5. The tube 17 is like tube 17and like parts are referred to by the same reference characters bearinga prime. The air inlet openings facing upstream, however, are indicatedat 30, 31, 32 and 33. The area of the opening 31 is greater than thearea of the opening 30. The area of the opening 32 is greater than thearea of opening 31 and the area of opening 33 is greater than the areaof opening 32. In other words, the areas of the openings spacedprogressively from the sensor 16 progressively increase.

As pointed out with reference to the tube 17, the total area of theupstream openings in the tube 17' are less than the area of opening 23'.Also, the cross-sectional area of the tube 17' is greater than the sumof the areas of the upstream openings.

The sizes of the openings 30, 31, 32, 33 can be determined bycalculating the required additional volume of air to be admitted througheach opening to compensate for the additional length of airflow to theoutlet 23' so that substantially equal volumes of air from all of theopenings will combine and flow around the transistor 16.

By the invention a relatively small sensor body can be made to respondto an average temperature or condition of an air stream havingvariations in various strata thereof. The invention is applicable tovarious types of air-conditioning systems other than air-coolingsystems, such as heating or humidifying.

We claim:

1. In an air-conditioning system including an air duct for conductingair subject to conditioning and a blower for moving air through saidduct, control means for said air conditioning system comprising arelatively small sensor element, and wall means forming an elongated airconduit extending transversely of a substantial portion of the stream ofair flowing in said duct and having a cross-sectional area substantiallyless than the cross-sectional area of said duct, a first section of saidwall means facing upstream of the airflow in said duct being open alonga substantial width of said duct and facing upstream of said duct toreceive air moving downstream in said duct in a plurality of areastransversely of said duct, said wall means having an opening in a secondsection thereof positioned to be shielded from the downstream airflow insaid duct, and means locating said sensor element to sense a conditionof air exiting through said open second section of said conduit.

2. An air-conditioning system as defined in claim 1 furthercharacterized by said wall means having a plurality of apertures thereinspaced apart along said first section.

3. An air-conditioning system as defined in claim 2 in which said wallmeans comprises a cylindrical tube closed at its ends.

4 An air-conditioning system as defined in claim 2 characterized by theareas of said apertures being of different values and increasing inareas for those apertures more remote from said sensor.

5. An airconditioning system as defined in claim 4 further characterizedby the sum of the areas of said apertures in said first section beingless than the open portion of said second section.

6. An air-conditioning system as defined in claim 2 furthercharacterized by the areas of said apertures being less than thecross-sectional area of the conduit formed by said wall means.

7. An air-conditioning system as defined in claim 1 furthercharacterized by the area of said open portion of said first sectionbeing less than the cross sectional area of the conduit formed by saidwall means.

8. An airconditioning system as defined in claim 1 in which said firstsection of said wall means facing upstream of the airflow in said ductis open so as to admit progressively greater volumes of air as thedistance from said sensor is increased towards the end of said wallmeans remote from said sensor.

9. An air-conditioning system as defined in claim 1 furthercharacterized by said second section of said conduit having an openingfacing downstream of the airflow in said duct.

10. ln an air-conditioning system including an air duct for conductinair subject to conditionin and blower for moving arr throu said duct,control means or said air-conditioning system comprising a relativelysmall sensor element, wall means forming an elongated air conduitextending transversely of a substantial portion of the stream of airflowing in said duct and having a cross-sectional area substantiallyless than the cross-sectional area of said duct, a said first section ofsaid wall means having means at intervals along a substantial portion ofsaid conduit operative to direct a plurality of segments of saidairstream into said conduit, said last mentioned means being operativeto introduce progressively larger volumes of said airstream into saidconduit at progressively greater distances from an open second sectionof said conduit said sensor element being located to sense a conditionof air exiting through said open second section.

11. An air-conditioning system as defined in claim 10 furthercharacterized by said means along said conduit comprising spacedopenings in said first wall section facing upstream of the airflow insaid duct, the areas of said spaced openings increasing with increase indistance thereof from said sensor element.

12. An air-conditioning system as defined in claim 11 in which saidspaced openings comprise rectangular openings of differing widths.

13. An air-conditioning system as defined in claim 10 furthercharacterized by said second section of said conduit having an openingfacing downstream of the air flow in said duct.

1. In an air-conditioning system including an air duct for conductingair subject to conditioning and a blower for moving air through saidduct, control means for said air conditioning system comprising arelatively small sensor element, and wall means forming an elongated airconduit extending transversely of a substantial portion of the stream ofair flowing in said duct and having a cross-sectional area substantiallyless than the cross-sectional area of said duct, a first section of saidwall means facing upstream of the airflow in said duct being open alonga substantial width of said duct and facing upstream of said duct toreceive air moving downstream in said duct in a plurality of areastransversely of said duct, said wall means having an opening in a secondsection thereof positioned to be shielded from the downstream airflow insaid duct, and means locating said sensor element to sense a conditionof air exiting through said open second section of said conduit.
 2. Anair-conditioning system as defined in claim 1 further characterized bysaid walL means having a plurality of apertures therein spaced apartalong said first section.
 3. An air-conditioning system as defined inclaim 2 in which said wall means comprises a cylindrical tube closed atits ends.
 4. An air-conditioning system as defined in claim 2characterized by the areas of said apertures being of different valuesand increasing in areas for those apertures more remote from saidsensor.
 5. An air-conditioning system as defined in claim 4 furthercharacterized by the sum of the areas of said apertures in said firstsection being less than the open portion of said second section.
 6. Anair-conditioning system as defined in claim 2 further characterized bythe areas of said apertures being less than the cross-sectional area ofthe conduit formed by said wall means.
 7. An air-conditioning system asdefined in claim 1 further characterized by the area of said openportion of said first section being less than the cross sectional areaof the conduit formed by said wall means.
 8. An air-conditioning systemas defined in claim 1 in which said first section of said wall meansfacing upstream of the airflow in said duct is open so as to admitprogressively greater volumes of air as the distance from said sensor isincreased towards the end of said wall means remote from said sensor. 9.An air-conditioning system as defined in claim 1 further characterizedby said second section of said conduit having an opening facingdownstream of the airflow in said duct.
 10. In an air-conditioningsystem including an air duct for conducting air subject to conditioningand a blower for moving air through said duct, control means for saidair-conditioning system comprising a relatively small sensor element,wall means forming an elongated air conduit extending transversely of asubstantial portion of the stream of air flowing in said duct and havinga cross-sectional area substantially less than the cross-sectional areaof said duct, a said first section of said wall means having means atintervals along a substantial portion of said conduit operative todirect a plurality of segments of said airstream into said conduit, saidlast mentioned means being operative to introduce progressively largervolumes of said airstream into said conduit at progressively greaterdistances from an open second section of said conduit, said sensorelement being located to sense a condition of air exiting through saidopen second section.
 11. An air-conditioning system as defined in claim10 further characterized by said means along said conduit comprisingspaced openings in said first wall section facing upstream of theairflow in said duct, the areas of said spaced openings increasing withincrease in distance thereof from said sensor element.
 12. Anair-conditioning system as defined in claim 11 in which said spacedopenings comprise rectangular openings of differing widths.
 13. Anair-conditioning system as defined in claim 10 further characterized bysaid second section of said conduit having an opening facing downstreamof the air flow in said duct.